1. Field of the Invention:
The present invention relates to an engine cycle control system for controlling an engine so that it operates in a two-cycle mode when the rotational speed of the engine is lower than a predetermined speed and in a four-cycle mode when the rotational speed of the engine is higher than the predetermined speed.
2. Description of the Prior Art:
Conventional engines are roughly grouped into two-cycle and four-cycle engines in view of different strokes per revolution of the output shaft of the engines.
In the two-cycle engines, since the explosion occurs each time the engine output shaft makes one revolution, the rotational speed of the output shaft suffers less fluctuations, and the engine can produce a high-torque output. However, since the intake and exhaust strokes are simultaneously performed in the two-cycle engines, the intake air and the exhaust gases are not fully exchanged particularly, and the two-cycle engines are lower in efficiency and higher in fuel consumption.
In the four-cycle engines, the explosion occurs each time the engine output shaft makes two revolutions, and the exhaust and intake strokes are independent of each other. Accordingly, the fuel consumption of the four-cycle engines is low. Since, however, the four-cycle engines suffer larger fluctuations in the rotational speed of the engine output shaft, the engine output torque is lower, and the engines do not operate smoothly in a low engine speed range.